Astonishing footage captures a rare Asian black bear leaving spectators in shock after unexpectedly attacking and pinning a performer to the ground during a circus act.

The video shows the bear named Xiong Xiong and two artists standing on stage in a circus in the city of Huzhou, in Zhejiang, China, on February 13.

But just seconds later the clip shows the animal suddenly tackling one of the performers to the ground, as this second one rushed to help his colleague break free from the bear's grip.

Chinese media reported that it took up to six circus staff to rescue the artist and place the bear in its cage, as stunned spectators watched in awe.

The Asian black bear (Ursus thibetanus) also known as the white-chested bear, is a medium-sized bear native to Asia. It is listed as 'Vulnerable' on the IUCN Red List of Threatened Species.

Populations are predominantly endangered by deforestation and poaching for their body parts, which are used in traditional medicine.